Abstract: For large areas depressed farmlands, ditches and other uneven terrain with side slopes and adjacent roads, deep excavation projects in these areas will mainly face the situations which differ from conventional deep excavations in urban areas. These differences are in natural ground floor elevations surrounding the excavated area and the variation of excavation depths. When it is not eligible to install ground anchors for the supporting structure, double-row piles and other conventional supporting structures without internal support with the limitation by the cost and/or environmental constraints, the concern of the independent supporting structure for the side excavation with different excavation depths could be effectively resolved by using site specific conditions, which is a combination of the “central island” (central structure blocks) and diagonal support members. This arrangement could avoid fully installing the internal support in a large area, thus is cost effective and efficiency. Further, using the main structure as part of the support system is reliable in the overall stiffness, can better control the deformation of the supporting structure and protect the environment.

Key words: Depressed Area, Uneven Excavation Depth, Central Structure Blocks, Deep Excavation, Side Slope